Two diameter punch for tube bender



y .9, 1970 P. v. GREGG 3,512,392

TWO DIAMETER PUNCH FOR IUBE BENDER I Filed May 1, 1968 1/7 WI M j,

VENTOR.

United States Patent M 3,512,392 TWO DIAMETER PUNCH FOR TUBE BENDER Paul V. Gregg, Racine, Wis., assignor, by mesne, assignments, to Tenneco Inc., Houston, Tex., a corporation of Delaware Filed May 1, 1968, Ser. No. 725,593 Int. Cl. B21d 9/05 US. Cl. 72-389 2 Claims ABSTRACT OF THE DISCLOSURE A press bender is adapted to bend a two diameter section of pipe by means of a punch and wing die configuration including a two diameter punch having the step between the diiferent diameters located on the midplane of the punch and the axis of the ram.

BRIEF SUMMARY OF THE INVENTION In the formation of tailpipes for automotive exhaust systems, ditficulty has been encountered in successfully bending pipes wherein there is a swaged or reduced diameter section which extends into a bend in the pipe. It is the purpose of this invention to provide a modification of a conventional press bender so that it can produce a bend in a two diameter pipe section. The invention accomplishes this by means of a punch and wing die configuration of different diameters with the step between them matching the step between the two diameters of the pipe section and preferably located on the center line of the punch.

In the drawings:

FIG. 1 is a simplified front elevation, partly in section, and with parts removed of a press bender embodying the invention;

FIG. 2 is a front view similar to FIG. 1, but showing the parts in position at the conclusion of the bend;

FIG. 3 is a bottom plan view of the punch shown in FIGS. 1 and 2; and

FIG. 4 is a side elevation of a two diameter pipe after it has been bent by means of the punch and wing die arrangement of this invention.

DETAILED DESCRIPTION OF THE INVENTION A vertical press bender 1 for bending tubes or pipes 3 has a ram 5 which moves along a vertical axis and carries a punch 7 at its bottom end which cooperates with wing dies 9 and 11 that are pivoted respectively on fixed pins 13 and 15. Upon downward movement of the ram 5 the punch 7 forces the pipe 3 downwardly against l the wing dies 9 and 11 which pivot downwardly about their pivot pins 13 and 15, as seen in FIG. 2, so that a bend is formed in the pipe 3.

The punch 7 is semicircular in shape and has a substantially semicircular channel or groove 17 formed in it to open out of the semicircular periphery 19. The wing dies 9 and 11 also have substantially semicircular channels 21 and 23 respectively opening out of their top faces 25 and 27 to cooperate with the punch channel 17 and substantially completely envelop a pipe being bent, as is evident from the drawings.

The pipe 3 has a swaged or reduced diameter end portion 3A which is connected by means of a stepped or shoulder portion 3B to a larger diameter portion 3C. With bending equipment previously available, it has been difficult, if not impossible, to form bends wherein the shoulder portion 3B is located within the bend section. In accordance with this invention, the two diameter pipe section is accommodated by the punch and wing dies so that both can be bent simultaneously. This is done by forming the wing die channel 23 and the punch channel section 17A on a diameter to suit the size of the section 3A of the pipe and correspondingly forming the wing die channel 21 and the punch channel section 17C on a larger diameter suited to the larger diameter section 3C of the pipe. The stepped or shoulder section 17B of the channel preferably lies on the center line of the punch 7 and falls in the gap 29 between the inner ends of the wing dies 9 and 11. The channel sections 17A and 17B preferably have grooves 31 and 33 formed in them to accommodate the excess metal on the inside of the bend in the pipe so that it forms the ribs 35 and 37 to minimize undesired distortion as pointed out in my copending application, Ser. No. 596,859, filed Nov. 25, 1966. As indicated in FIGS. 1 to 3, the punch 7 may be made up of two half sections 7A and 7B which can be welded together along the joint 39 that is on the midplane of the ram 5. While the channel 17 is stepped in depth and in diameter, it will be seen that the outer periphery 19 of the punch 7 is continuous and likewise that the faces 25 and 27 of the wing dies 21 and 23 are coplanar. t

In operation the pipe 3 is inserted until the shoulder 3B contacts the step 17B in the punch 7 or the inner end of the channel 23. The ram 5 is then depressed as shown in FIG. 2 resulting in the formation of the bend so that the pipe appears as shown in FIG. 4.

Modifications may be made Without departing from the spirit and scope of the invention.

I claim:

1. In a press type tube bender having a ram, a punch attached to the ram and movable with it and having a groove formed in its bottom surface for receiving and engaging the pipe to be bent, a pair of movable wing dies aligned with the punch and each having a groove 10 receive a pipe to be bent, the groove on the punch having two sections each of different diameter than the other, each of said wing dies having a groove of a diameter corresponding to and cooperating with a groove section on the punch whereby the punch and wing dies are capable of bending a tube having two different diameters.

2. A bender as set forth in claim 1 wherein the two sections meet along a plane coplanar with the midplane of the ram.

References Cited UNITED STATES PATENTS 3 1966 Callendar 72-3 69 2/ 1969 Huth 72-389 U.S. Cl. X.R. 72369 

